The treatment of greywater and blackwater is crucial for the protection of the environment. What is it and what are the treatment options? This article gives an overview of properties and solutions.
Greywater and blackwater – origin, treatment, and disposal
What is blackwater?
Blackwater is wastewater from toilets. It contains urine and faeces and is put into the sewage system together with toilet paper. Together with the flushing water, each person produces between 25 and 50 litres daily. The treatment usually takes place in municipal sewage treatment plants, but in some cases direct treatment is necessary. This is the case when houses are not connected to the public sewer system and therefore no discharge is possible. In this case, a small wastewater treatment plant is worthwhile. Likewise, treatment of blackwater is necessary at campsites, which are often located in remote areas and do not have a connection to a stationary sewage treatment plant.
The name “blackwater” is derived from the bacterial decay process. The resulting colour gives the wastewater its name. In contrast to other wastewater streams, blackwater has a large proportion of organic substances. Due to a high phosphate and nitrogen content, it is particularly rich in nutrients, which increases above all the biological oxygen demand (BOD5) and the chemical oxygen demand (COD). In contrast to all other wastewater streams, black water is often contaminated with pathogens and drug residues.
What is greywater?
Greywater is only slightly polluted, as it is wastewater that is produced when washing hands, showering, or bathing. In addition to dirt, detergents and cleaning agents are therefore also found in greywater. This not only occurs in single- or multi-family homes, but also on campsites and in schools, as well as in industrial enterprises such as laundries. The amount of greywater that is produced therefore varies from application to application. While private households produce about 40 litres of greywater per day, industrial enterprises can produce several thousand litres of greywater per day.
The impact of greywater and blackwater on the environment
Greywater and blackwater can have a significant impact on the environment should no treatment take place. Chemical residues such as detergents, but also the high organic load leads to severe pollution of lakes and rivers. Therefore, the application possibilities for wastewater treatment are versatile – tailored to each individual application.
In the private sector, the treatment of greywater and blackwater has a positive impact on the environment. If a household has the option of installing a small wastewater treatment plant, the treated wastewater is particularly suitable for underground irrigation of the lawn. Via a drainage system that runs through the garden, the treated wastewater reaches all the desired areas. On the one hand, this ensures that the lawn is always green, even on hot days, and at the same time feeds the groundwater table. When treated grey and black water infiltrates, it flows through various layers of soil until it encounters an impermeable layer. As a result, filtration takes place. After this water has been pumped, it can be returned to the drinking water cycle, after possible treatment.
On an industrial level, a biological solution is particularly suitable for the treatment of grey and black water. A particularly large number of microorganisms are dissolved in this type of wastewater. In combination with the high organic load, an active sludge is quickly formed, which reliably respires the pollutant loads. Depending on the requirements and additional modules, the wastewater is suitable either for direct discharge or for transfer to a municipal wastewater treatment plant.
The treatment solutions
PPU offers various solutions for the treatment of greywater and blackwater. At the private level, the ClearFox® Nature is a particularly popular system. The small wastewater treatment plant works completely without electricity, which reduces operating costs to a minimum. It is suitable for above ground and below ground installation. Repairs or replacement of spare parts are virtually unnecessary, as the ClearFox® Nature is a robust and particularly durable small wastewater treatment system.
For larger applications, a ClearFox® SBR system is generally worthwhile. This can be easily adapted to the individual wastewater volume and dirt load. Almost any tank is suitable for installation. The shape is irrelevant, only the minimum size for the wastewater volume must be observed. An underground concrete tank in which the customer installs the SBR system is often worthwhile. Therefore, above all, the transport costs are kept to a minimum.